The only legal
firewood is a "cord" and parts of a cord
or cubic meter.
A cord is the firewood contained in 128
cubic feet of space when tightly stacked
A cord of firewood is a pile measuring 4-ft. wide, 4-ft. high and 8-ft. long. Whatever the dimensions of the pile, it must be equivalent to 128
cubic feet of tightly stacked firewood to be one cord.
More info at: oregon.gov//ODA/MSD/Fuel_facts.shtml